Quantifying dinoflagellate parasites in coastal copepods by digital image analysis
Parasites and diseases are key structuring components across all biological systems. Yet, the understanding of their role in marine pelagic systems remains in its infancy (e.g., Lafferty et al. 2008). Planktonic copepods are crucial in shaping pelagic ecosystem dynamics as well as global energy and nutrient fluxes through their roles as predators, prey and sedimentation vehicles, and via their interactions with the microbial food web as substrate generators. Copepods are also primary and intermediate hosts of many eukaryotic parasites, but the role of these parasites in shaping their biology and population dynamic remains largely unknown. Understanding the role of parasites as structuring mechanisms is fundamental for the understanding of pelagic food webs at large, especially given the overall stress induced by fisheries and contemporary environmental challenges.
Presently we lack both necessary observational data and theoretical foundations to fully comprehend the impact of parasites on the dynamics of coastal copepods. Observational data should ideally include both abundances of free-living parasite stages and prevalence of infected copepods, but the former has proved elusive. Many important copepod parasites are dinoflagellates. As all dinoﬂagellates have condensed chromatin at all stages of their life cycle, they will give a strong and distinct fluorescence signal when stained with DNA probes like propidium iodide (Alves-de-Souza et al. 2011). We expect this property to have potential for fast and efficient quantification of dinoflagellate infections in natural communities of coastal copepods.
In this Master’s project, you will develop, implement, and test a practical protocol for counting dinoflagellate parasites in propidium iodide-stained copepods. The project involves field and laboratory work, as well as processing, archiving, and analysis of digital epifluorescence images. Depending on your interests and qualifications, we can also develop the project deeper into directions like robotics, image recognition, and machine learning. Your work will be integrated with an on-going PhD project, as well as several other Master’s project.
Alves-De-Souza, C., Cornet, C., Nowaczyk, A., Gasparini, S., Skovgaard, A., & Guillou, L. (2011). Blastodinium spp. infect copepods in the ultra-oligotrophic marine waters of the Mediterranean Sea. Biogeosciences, 8: 2125-2136.
Lafferty, K.D., S. Allesina, M. Arim, C.J. Briggs, G. De Leo, A.P. Dobson, et al. (2008). Parasites in food webs: the ultimate missing links. Ecology Letters, 11: 533-46.